(a) Field of the Invention
The present invention relates to a method for classifying a quality of service (QoS) for a packet in a portable Internet system.
(b) Description of the Related Art
A portable Internet system is an Internet protocol (IP)-based wireless communication network, and a terminal of the portable Internet system generates a time-sensitive voice over Internet protocol (VoIP) packet, real-time packet data corresponding to a video data stream, and non-real-time packet data including a web-browsing service. In the portable Internet, traffic for transmission includes four QoS classes. The four QoS classes are respectively categorized into an unsolicited grant service (UGS), a real-time polling service (rtPS), a non real-time polling service (nrtPS), and a best effort (BE) service.
The UGS supports real-time transmission of small size packets such as a voice over Internet Protocol (VoIP), and the rtPS supports transmission of variable size packets such as a moving picture experts group (MPEG) video on a periodic basis. In addition, the nrtPS supports transmission of variable size data bursts (e.g., a file transfer protocol, FTP), and the BE service supports transmission of traffic having lower priority such as e-mail and web-browsing. The above-noted service grades are combined with QoS parameters such as a traffic rate, a jitter, a maximum latency, and an error rate, and associated with a specific transport connection. That is, the transport connection is associated with one of the QoS grades. A plurality of transport connections may be established between a terminal and a base station depending on QoS, and each transport connection can be identified by a connection identifier (CID).
Packet data between the terminal and the base station in the portable Internet system can be communicated through the transport connection established in a medium access control (MAC) layer. specifies connection-oriented access methods. In addition, mapping of an IP packet to a transport CID is designed to be performed through a packet classifier.
The packet classifier classifies packet data into a transport CID of the MAC layer by using the header information of the IP packet transmitted from an upper layer. The terminal needs an uplink packet classifier to classify uplink IP packets toward the base station, and the base station needs a downlink packet classifier to classify downlink IP packets toward the terminal.
The packet classifier defines a plurality of classification rules for classifying IP packet into a transport CID, and the classification rules are composed by a combination of IP header information including a type of service, a destination address, a source address, a destination port number, a source port number, and a protocol type. A packet classifier is connected with only one CID. Thus, in the portable Internet system, an IP packet is classified into a transport CID having a specific QoS class by the packet classifier and then transmitted. Therefore, an application having a real-time service parameter must be mapped to a transport CID having the same QoS class (i.e., real-time service) and a packet classification rule of a packet classifier must be accurately established such that the application can be served with real-time services.
A process for generating a packet classification rule is the same as that of a service flow of a MAC layer. The service flow is generated, changed, and deleted through standardized processes such as a dynamic service add (DSA) process, a dynamic service change (DSC) process, and a dynamic service delete (DSD) process. In the DSA process, QoS parameter and a packet classification rule are transmitted between the mobile station and the base station. The mobile station and the base station generate uplink/downlink packet classifiers and uplink/downlink CIDs by exchanging the QoS parameter and the packet classification rule.
However, it is difficult to identify a QoS class of IP packet. In a conventional bi-directional communication network it is not designed to classify the QoS parameters of IP packet, and the terminal and the base station transmit identically the IP packets by a first-in-first-out (FIFO) method even though the IP packets have different QoS classes.
On the other hand, an application program may insert QoS class information into a specific field of IP header for classification of IP packet. However, this method also has problems of developing an application dedicated to a portable Internet service and accordingly the application becomes incompatible with other typical applications.
The Internet Assigned Number Authority (IANA), an international Internet standardization organization, assigns a well-known port number for an application such that a client program accesses a server by using the well-known port number. For example, a file transfer protocol (FTP) uses port 21, specifying transmission control protocol (TCP) or user control point (UCP) as a transport protocol, and a packet having the same protocol type and port number as above may have the same QoS as that of the FTP. However, it could be inaccurate to classify packets by using the protocol type and port number when substantial traffic data is transmitted/received because the protocol type and port number are used when the client initially accesses the server and they may be dynamically changed after the initial access.
According to another method, forming the IP address of an Internet server and a characteristic of service as a classification rule can be a candidate solution. However, this method also has problems of difficulty due to variation of the IP address and inefficiency of managing addresses of all existing Internet servers.
The above-state methods cannot solve the problems such as how to identify a QoS class of IP packet and how to generate a classification rule of the packet. Accordingly, a method for identifying a QoS grade of IP packet and generating a classification rule is needed.